Re: [PATCH wpan-tools] mac: range checking for command accepting only 0 or 1

[Alexander Aring <alex.aring@gmail.com>]

On Wed, Aug 19, 2015 at 04:28:33PM +0200, Stefan Schmidt wrote:
> Hello.
> 
> On 19/08/15 16:22, Alexander Aring wrote:
> >Hi Stefan,
> >
> >On Wed, Aug 19, 2015 at 04:13:24PM +0200, Stefan Schmidt wrote:
> >>lbt and ackreq_default only accept 0or 1 as arguments which we did not
> >>acount for so far. Testing invalid arguments and checking teh return
> >>code uncovered this one.
> >>
> >>Signed-off-by: Stefan Schmidt <stefan@osg.samsung.com>
> >>---
> >>  src/mac.c | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >>diff --git a/src/mac.c b/src/mac.c
> >>index 76db58f..26c6fc5 100644
> >>--- a/src/mac.c
> >>+++ b/src/mac.c
> >>@@ -175,6 +175,8 @@ static int handle_lbt_mode(struct nl802154_state *state,
> >>  	mode = strtoul(argv[0], &end, 0);
> >>  	if (*end != '\0')
> >>  		return 1;
> >>+	if (mode != 0 && mode != 1)
> >>+		return 1;
> >>  	NLA_PUT_U8(msg, NL802154_ATTR_LBT_MODE, mode);
> >>@@ -202,6 +204,8 @@ static int handle_ackreq_default(struct nl802154_state *state,
> >>  	ackreq = strtoul(argv[0], &end, 0);
> >>  	if (*end != '\0')
> >>  		return 1;
> >>+	if (ackreq != 0 && ackreq != 1)
> >>+		return 1;
> >range checks should be handled by kernelspace. Currently we do a "!!var"
> >conversion there.
> 
> Which is why any value > 0 gets set to 1 here.
> 
> >Maybe we should change it there and accept "1" or "0".
> 
> I think that would indeed be better.
> 
> >We should never handle "if a range is valid or not" inside userspace,
> >otherwise other applications which talking to nl802154 can do a
> >different handling then.
> 
> I disagree here. We should for sure do range checking in the kernel but we
> should as well check for it in iwpan and get the return code right.
> 

this should be handled by returning -EINVAL in the handler of nl802154. Try a:

iwpan dev wpan0 set max_frame_retries 8

which should always return "-EINVAL" inside nl802154.

The return is:

command failed: Invalid argument (-22)



Is this okay? Or do you expect a different handling?

- Alex